Corbin's Treehouse - Corbin Dunn, Santa Cruz, CA
Plug Bug

The 'Machining' Category

New Corbin UniBar (unicycle handlebar)

I made a new handlebar for my geared KH26. I was using the KH T-bar, but it feels really flexy and it feels like the seat will eventually break from the pressure I put on it. I had already made a slightly longer and slightly wider T for it out of CroMo steel, but it was just as light as the aluminum original. Here’s the new bar, completed and installed: New bar, 352 grams: Old bar plus the seat strengthen plate (not needed with my design): So, 150 gram savings in weight by using CroMoly steel. And it is a... [read more]

Making the LED Cyr Wheel / Roue Cyr – version 1

Here are my rough notes about making my LED cyr wheel (version 1). A Video can be seen here. Edit: 12/28/2013: Here are some problems I am having with this  LED Cyr Wheel v1 I used a new technique for bending wheels; this time, I used a cheap Harbor Freight rolling bender with modifications from the 4×4 Forums that provide “weld on” wings, and the ability to make it motorized with a Harbor Freight pipe threading machine. I couldn’t roll the complete circle with it attached to my stand below: (the picture shows it fully rolled, but it was AFTER... [read more]

Coffee Cup Stirling Engine

Over winter break I started on a project I’ve been wanting to do for a long time. A coffee cup stirling engine, made from scratch based on plans from Jan Ridders. It “almost works”. The bearings seem to be too big, and the shaft has a lot of slop. I had machined the shaft to the side I thought the bearings were going to be (3mm), but they are larger! I need to remake that part and see if it works. Some work in progress shots. Power piston (graphite), cylinder (brass), crank shaft (steel), flywheel (alum), stand (alum in brass).... [read more]

Corbin V-36

I’m working on a V-Frame 36’er unicycle, called the “Corbin V-36“. It’s partially an experiment to see how light I can make it, yet still be strong and not flex. I did a 3d model in Sketchup, and printed it full size. I then machined a jig to hold things in place. Here’s a video explaining the jig: And some pictures. The jig setup for my my main seat post tube: Experimenting with bending: I’m using cro-moly tubing, 1/2″ OD by .049 wall thickness. It is too small of tubing, and the frame flexes when going up hills. I’m going... [read more]

Plug Bug: Broken brake…

…well, problems come in pairs. I changed my front brake pads about about 8600 miles; they wore away quickly! I didn’t change the rear, as they weren’t as bad as the front. I checked the new front ones at 15,000 miles and they are doing great. I had looked at the rear but only on one side and without taking the wheel off. They looked okay, so I wasn’t going to do them yet. However, the rear brakes started making a horrible noise last Friday. So today I decided to take the brakes apart and drop in the new pads... [read more]

Roue Cyr: Making a wheel – skinning

I’m doing a series of videos on how I made my second Roue Cyr (Cyr Wheel — aka: Simple Wheel). Here’s the last in the series…which is skinning. Updated notes: Use pipe clamps to secure the air attachment on! Heat it in the oven for ~3 minutes. Spray water on it from a bottle if it has trouble going over. If this method doesn’t work, the alternative is to skin the wheel while it is hot bath water, and then let it dry out for a few days before assembling. How to skin a roue cyr wheel Email me if... [read more]

New pull up bar

Using the plasma cutter to make stuff… I wanted a new pull-up bar for my house. The old one looked tacky…but how can anything be tacky around your own house if you put it there? Here’s some shapes cut out of metal: Pieces setup for welding: Ugly pullup bar removed: Hanging on the wheel (as seen through the eyes of a lyra. And in this picture you can see how the top right of the lyra wasn’t quite as circular as I wanted…)

Cube Hanger

I needed somewhere better t hang my cube when I wasn’t using it. So, I made a cube hanger! I used the plasma cutter to cut some pieces of 3/16’ish steel plate (from the scrap yard): Cut out: I TIG welded on some 1.5″ pipe at a 45 angle: Cleaned it up, and powder coated it flat black: Bolted it to my beam (it is super strong!): And hang the cube! It is a little close to the wall, but out of the way. It is kind of fun to sit in it, so I’ll probably whip up another one... [read more]

Metal Coat Rack

What a better use for an old VW brake drum? A few in progress shots: Initial sketch and idea:

Plasma Cutter

I got a new tool a few weeks ago. A plasma cutter! After doing some research, I went with a Thermal Dynamics Cutmaster 52. It is awesome! I also had to get a new air compressor to keep up with it. I went with a Husky one from Home Depot; it has a three year warranty, whereas most other ones of the same size have a 1 year warranty. Plus, there were lots of good reviews on

Shop Tour

How about a tour of my garage shop? Grinder: Work desk and tools hanging on the wall: The fan in the window is used to exhaust fumes from welding and other things: Nuts, bolts and Bengal cat: JET drill press: Metal stock: MATCO welder (I bought it used) and oxy-acetylne setup behind it to the left: Grizzly G0555 wood bandsaw. Works well for the small shop, although a few times I have wanted a wider throat. Grizzly 8″ jointer; I bought a good large jointer, but I have only used it a few times so far: The dust collection system... [read more]

Turner’s Cube

Tuner’s Cube. I made it for my dad for Christmas 2010. Aaron helped me over Thanksgiving break to figure out the details and did some machining on it too. It started out as a ~3.5″x3.5″ solid square piece of aluminum. We made a jig to hold it so it could be removed and place back in again at the same position but on a different edge. The rotary table on the mill was used to turn it out: Second half of the jig — this was Aaron’s idea, and it worked great. Just use a piece of mild steel with... [read more]

Metalwork: Wine Glass Rack

Here’s a wine glass rack I made for my dad’s wife, Karen. I made it a while ago, but it was a Christmas present, so I couldn’t post it till after the 25th. It is made out of 1/4″ diameter mild steel round stock. I bent each top piece by hand, freestyle around a little jig. I welded each one to the other one at the base. To cover up the welds, I wanted to curl some of the round stock around it; I tried to pre-bend it by hand, but that wasn’t working. Instead, I started by tacking the... [read more]

Plug Bug: Turning the flywheel

An electric motor doesn’t need a big flywheel to keep the engine running. It also doesn’t need the starter gear teeth around the edge. In fact, all it really has to do is engage with the clutch disc via the pressure plate. I’m not sure how beefy that needs to be, but I decided to take down a bit of the flywheel size on my old south bend lathe. Here’s the tranny, coupling adapter, and flywheel: I bolted the coupling adapter to the flywheel; it didn’t come with the right bolts, and I had bought some grade 5 bolts that... [read more]

New DRO on the Mill

Back in April I bought a Anilam Wizard 411 DRO (Digital Read Out). My old one broke when Jason accidentally moved the X-axis too far (which was totally my fault — I should have checked the stops and made sure it wouldn’t happen). It wasn’t all that bad, as it gave me a reason to add the Z axis for the knee. So, I was about to buy the Grizzly 3 axis DRO (literally had it ordered) when I got a 20% off email from ENCO. That made the totally sweet Anilam almost the same price, so I cancelled the... [read more]

Steel Bending Jigs

I’ve been working on creating a railing for the upstairs portion of my house. I wanted to create it out of steel and have some cool curves in it. I needed a bending jig, and after experimenting with wood I realized it wouldn’t withstand the forces I was exerting on it for the curves I wanted. So, I made one out of steel. The jig is just clamped to my table. It consists of some 3/16″ steel (I think) hand bent to the curve I wanted. The circular tube piece is to act as a strong resistance to the bend.... [read more]

Recumbent Unicycle

The Recumbent Unicycle. Not a pretty beast, and not easy to ride. It took me thee weeks of practice before I could ride it, and only after that could I “sort of” ride it. No free mounting or anything crazy like that. The balance point is just crazy difficult compared to a regular unicycle. Here’s a video of me riding it on 1/31/2010: I still plan to “shine it up” and build a small backrest. I originally wanted a nice large backrest, but I decided that it would hinder the ride ability of it. Here’s the building process, which went... [read more]

Adjustable Unicycle Handlebar

I was never happy with the last handlebar I made for my KH36 road unicycle. It attached underneath the base of my seat, and despite it being carbon fiber it still flexed quite a bit and I was afraid it would break. It also never felt quite right — I wanted it to be slightly lower, and slightly more forward. On my KH24 geared muni I have a handlebar that attaches to the seat post and has always felt great. Using the seat post wouldn’t work for my KH36, since I’m short and run the seat all the way as... [read more]

Building a Tandem Unicycle

My last post introducing my Tandem Unicycle originally started out with a step-by-step process of how I built it, but for some reason I lost the post. Here is how I made my tandem uni: This idea is not my original idea. A few years ago at a “California Mountain Unicycle Weekend” a guy named LobbyBobster on the unicycle forums brought one and I gave it a try with Beau Hoover. Here’s a picture of the creator and their tandem, which looks much nicer than mine! So, from seeing this uni two years ago and based loosely on this picture... [read more]

Aerial Cube

I just finished another project: the Aerial Cube. Louise and I saw the cube at a circus show last week, and I thought “Hey, I could make one of those!”, and Louise asked “Can you make me one of those?”. So, here it is! The cube is made out of 1″ tubing that is 1/8″ thick. I bought it at a local metal place – “Sims Metals”. I cut 45’s with my little Grizzly horizontal bandsaw: And drilled+tapped some holes into a piece of steel to create a jig to hold the tubes at 90 degrees: And then welded two... [read more]

First Machining Project: Vise Stop

Every machinist needs a good vise stop. Here is mine, 100% completely made from raw steel, except for the bolts bolting it to the vise (which are too long — I need to buy new ones): The knurled wheels use split collars to tighten the bolts down. The larger knurled ones work much better than the smaller ones (require less force to tighten the things down), and I may make some more larger ones. So, how did this project come to finally being finished? I searched the net and found some great links on things people had done. I initially... [read more]

Milling machine tune up

My 1990 Enco Milling machine was starting to get quite a bit of shake at certain speeds. It has a variable speed head, and one of my friends, Bevan, recommended against getting the vari-speed, since they are sometimes prone to having trouble. But, I really do love being able to dial in the speed with the turn of a small wheel, and even though it was a pain to do, I tuned up the head and now it runs smooth again. I took the head apart, carefully labeling stuff on my bench: The main problem was a bad v-belt. The... [read more]

MIG welder

I picked up a used MIG welder a few weeks ago. The thing is totally cool; MIG is the way to go (Bronson was right!). I already used it to weld a few little things; a custom grinder stand, and a little piece of steel to a nut. These are things that would have been a pain to do with the oxy-acet torch.

One ounce removed off KH Moment cranks

Joseph Campbell came over last weekend to ride trials. He was mentioning how heavy the KH cranks are, so I told him we could quickly mill out some material. I took a deep pocket out of the bank of them and removed one ounce form each crank. The cranks started out at about 11 oz and ended up at 10 oz each. The chips on my mill: UPDATE: How about I spell “ounce” and not “once”.

Custom machined V-brake adapter for magura brake mounts

I made this on Saturday out of aluminum: a machined adapter that lets me attach a v-brake to magura brake mounts of my unicycle. The picture below (iPhone quality, sorry!) shows the first one, which was a little larger than #2. The hole for the spring is better on the second one.

Machining a unicycle clamp

I needed a brake adapter for my KH36 to go with a new handlebar I made. I finished the handlebar a few days ago to replace my red one. The red one was made of thick steel, and doesn’t have quite the right angle I want. Old red one on the left, new one on the right: I also need a brake adapter, since the magura brake will not fit on the bar ends. I had some cromoly tubing that was the wrong inner diameter, and way too thick. I used the lathe to turn the tube to the correct... [read more]

HDR shot of my lathe

A South Bend 13″ Tool Room Lathe from the 50’s:

(c) 2008-2017 Corbin Dunn

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